1. Field of the Invention
The present invention relates to novel light stabilizing flame retardants, and more particularly, to hindered amine light stabilizing groups which are bonded to halogenated flame retardants, and methods for preparing the same. Further, the present invention is directed to methods for stabilizing polymers or copolymers against the deleterious effects of heat, light and/or combustion.
2. Description of the Prior art
Flame retardancy using bis-imides has been disclosed by several sources. For example, British Pat. No. 1,287,934 discloses the use of bis-imides as flame retardants for polymers of olefinioally unsaturated aromatic monomers, such as polystyrene and styrene copolymers. Tetrahalophthalimides (halogen-containing bis-imides) have been used as flame retardants in high melting polymers as disclosed in U.S. Pat. No. 4,581,396. D. S. Pratt et al., "Phthalic Acid Derivatives: Constitution and Color, Some Derivatives of Tetrabromophthalimide," Journal of the American Chemical Society, 40:1415 (1918) and S. M. Spatz, et al., "Some N-Substituted Tetrabromophthalimide Fire Retardant Additives", Industrial and Engineering Chemistry; Product Research Development, Vol. 8, No.14, 397-398 (1969), both specifically disclose tetrabromophthalimide. Spatz additionally disclose several specific alkyl tetrabromophthalimides. Other tetrahalophthalimides are disclosed in U.S. Pat. Nos. 3,623,495; 3,313,763; and 3,240,792.
The combination of flame retardant imides with groups bonded thereto have been described. For example, European Patent Application No. 188,767 discloses N-substituted tetrahalophthalimides where the substituent on the nitrogen is an alkyl trialkoxysilane. In addition, a U.S. Pat. No. 4,003,862 discloses N-substituted tetrahalophthalimides where the substituent on the nitrogen is an alkyl haloalkylphosphate. Further, U.S. Pat. No. 4,520,146 and German Offenlegungsschrift No. 2,506,775 disclose N-substituted tetrahalophthalimides where the nitrogen substituent contains a hindered phenol antioxidant group.
European Patent Application No. 101,785 (CA 101 24547p) also discloses N-substituted tetrahalophthalimides where the substituent on the nitrogen is a tetrazole group (a blowing agent).
U.S. Pat. No. 4,465,571 further discloses imides of chlorendic anhydride where the nitrogen substituents are thiodipropionyl amino groups. These compounds are claimed to be useful flame retardants and antioxidants for polymers such as polyolefins as well as synergists for antioxidants used in the polymers.
None of the prior art, however, discloses N-substituted halophthalimides or N-substituted halonorbornene dicarboximides where the nitrogen substituent contains a light stabilizer group, specifically a hindered amine light stabilizer group.
Synthetic polymers, such as polyolefins (e.g.: polyethylene and polypropylene) styrenics (e.g.: polystyrene, rubber modified polystyrene and acrylonitrile-butydiene-styrene (ABS)), polycarbonates, polyesters and polyphenylene ethers, to name a few, are subject to degradation and discoloration upon exposure to heat and/or light with consequent deterioration of mechanical and other properties. These compounds are highly flammable and it is desirable to render them flame retardant.
Hindered amine light stabilizers having the 2,2,6,6-tetraalkylpiperidinyl structure have been found to be very effective in stabilizing polymers, such as the examples listed above, against the deleterious effects of heat and light, while tetrahalophthalimides and halonorbornene dicarboximides are known flame retarding additives for these polymers, among other polymers. In addition, the diacylhydrazide function is known to provide a particularly useful antioxidant function (see U.S. Pat. No. 3,639,334) and also acts as a metal deactivator by chelating metal ions, such as copper ions (see U.S. Pat. Nos. 4,147,689; 4,465,571 and 3,887,518), which metal ions are known to accelerate the photooxidative degradation of many polymers (see, e.g., Z. Slama, Plaste Kantsch., (1979) 25:256 CA 91:92331p).
It would be desirable to have a hindered amine light stabilizing group attached to a flame retardant group by an N-(acylamino)imide linkage or a diacylhydrazide linkage to protect polymer systems from the effects of light, heat and combustion.